Background Intelligent Transfer Service (BITS) is a component of modern Microsoft Windows operating systems that facilitates prioritized, throttled, and asynchronous transfer of files between machines using idle network bandwidth. It is most commonly used by recent versions of Windows Update, Windows Server Update Services, and Systems Management Server to deliver software updates to clients, and is also used by Microsoft's instant messaging products to transfer files. BITS is exposed through Component Object Model (COM), making it possible to use with virtually any programming language.